optimizers_lazyadam.ipynb

Kernel: Python 3

Copyright 2020 The TensorFlow Authors.

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TensorFlow Addons 优化器：LazyAdam

在 TensorFlow.org 上查看

在 Google Colab 中运行

在 GitHub 中查看源代码

下载笔记本

概述

此笔记本将演示如何使用 Addons 包中的 Lazy Adam 优化器。

LazyAdam

LazyAdam 是 Adam 优化器的一种变体，可以更高效地处理稀疏更新。原始的 Adam 算法为每个可训练变量维护两个移动平均累加器，这些累加器在每一步都会更新。此类为稀疏变量提供了更加懒惰的梯度更新处理。它仅更新当前批次中出现的稀疏变量索引的移动平均累加器，而不是更新所有索引的累加器。与原始的 Adam 优化器相比，它可以大幅提高某些应用的模型训练吞吐量。但是，它的语义与原始的 Adam 算法略有不同，这可能会产生不同的实验结果。

设置

!pip install -U tensorflow-addons

import tensorflow as tf
import tensorflow_addons as tfa

# Hyperparameters
batch_size=64
epochs=10

构建模型

model = tf.keras.Sequential([
    tf.keras.layers.Dense(64, input_shape=(784,), activation='relu', name='dense_1'),
    tf.keras.layers.Dense(64, activation='relu', name='dense_2'),
    tf.keras.layers.Dense(10, activation='softmax', name='predictions'),
])

准备数据

# Load MNIST dataset as NumPy arrays
dataset = {}
num_validation = 10000
(x_train, y_train), (x_test, y_test) = tf.keras.datasets.mnist.load_data()

# Preprocess the data
x_train = x_train.reshape(-1, 784).astype('float32') / 255
x_test = x_test.reshape(-1, 784).astype('float32') / 255

训练和评估

只需用新的 TFA 优化器替换典型的 Keras 优化器

# Compile the model
model.compile(
    optimizer=tfa.optimizers.LazyAdam(0.001),  # Utilize TFA optimizer
    loss=tf.keras.losses.SparseCategoricalCrossentropy(),
    metrics=['accuracy'])

# Train the network
history = model.fit(
    x_train,
    y_train,
    batch_size=batch_size,
    epochs=epochs)

# Evaluate the network
print('Evaluate on test data:')
results = model.evaluate(x_test, y_test, batch_size=128, verbose = 2)
print('Test loss = {0}, Test acc: {1}'.format(results[0], results[1]))